firefoxs' hello addon always sets off my antivirus with a riskware warning that "npfirefoxplugin.dll" is being blocked. How do I delete "Hello"?

I need to know what is causing my antivirus program to block "npfirefoxplugin.dll" every time i open firefox. There must have been an update which installed 2 new plugins. One is the "Hello" plugin and the other is the "share this page" plugin. I believe it's the Hello plugin. How do I remove or disable these or do you have another suggestion as to cause? Don't think I'll ever use either one of these